1. Field of the Invention
Embodiments relate to a reflective sheet, and more particularly, to an open-type color reflective sheet and a method of manufacturing the open-type color reflective sheet that may represent a variety of colors while maintaining brightness and visibility.
2. Description of the Related Art
Reflective sheets for enhancing visibility by reflecting, for example, specularly reflecting, incident light are widely used. Reflective sheets may facilitate identification of predetermined patterns or characters displayed on reflective sheets. Typically, a reflective sheet is attached to road signs, clothes, shoes or advertisements by an adhesive or sewing. For example, reflective sheets may be attached to clothes of people who work on the road or in dangerous places, such as sanitary workers, fire fighters or construction site workers, and may be used to identify a location of a person wearing a reflective sheet. Accordingly, reflective sheets may be very effective for protection and safety of people who wear the reflective sheets. In addition, when a reflective sheet is used for a road sign, the reflective sheet may reflect light emitted from headlights of a vehicle directly toward a driver during nighttime driving, to enhance recognizability of the road sign.
Reflective sheets are generally classified into cube-corner type reflective sheets and bead-type reflective sheets. Typically, in a cube-corner type reflective sheet, a plurality of prism polyhedrons having a shape of a triangular pyramid are used as reflectors, and in a bead-type reflective sheet, glass beads are used as reflectors. FIG. 1 is a cross-sectional view illustrating a cube-corner type reflective sheet 1 according to a related art.
Referring to FIG. 1, in the cube-corner type reflective sheet 1, an adhesive resin layer 20 is partially formed between a base film 10 and a retroreflector 30, and an isolation space 22 is formed between portions of the adhesive resin layer 20 so that the portions of the adhesive resin layer 20 are bonded through a thermal compression. The retroreflector 30 includes a protective film 32 formed of a thermosetting synthetic resin, a cube-corner layer 34 formed of a thermoplastic synthetic resin, and a cube-corner element 36 processed in a form of a triangular pyramid by performing patterning by pressing the cube-corner layer 34 in a heated mold. The cube-corner element 36 may protrude to increase reflective brightness of the cube-corner type reflective sheet 1 and enhance visibility of the cube-corner type reflective sheet 1. However, because the cube-corner element 36 protrudes to enhance the visibility, an adhesive strength may decrease due to a small contact area to the adhesive resin layer 20, which may allow the base film 10 to be easily peeled off. In addition, due to a penetration of rainwater or foreign substances into a side of the cube-corner type reflective sheet 1, the reflective brightness and the visibility may decrease, and durability of the cube-corner type reflective sheet 1 may also decrease.
A bead-type reflective sheet in Korean Patent Publication No. 10-2011-0084667, published on Jul. 26, 2011 mainly includes, as reflectors, a plurality of transparent microspheres, for example, glasses. In a bead-type reflective sheet using glass beads as reflectors according to the related art, the glass beads and a gray aluminum paste layer used to increase reflectivity of the glass beads are exposed on a surface of the bead-type reflective sheet, to enhance reflective brightness for retroreflection of incident light.